She’s been doing the same bit about my weight since I was fourteen years old — always the same shape of comment, always delivered with the same easy laugh, always followed immediately by “I’m only teasing” before I’ve even had time to react one way or the other. I’m thirty-one now. Seventeen years, give or take, of the same joke, and I still laugh on cue every single time, an automatic reflex I’ve never once managed to override no matter…